Magnetic field sensors generally include a magnetic field sensing element and other electronic components. Magnetic field sensors provide an electrical signal representative of a magnetic field sensed by the magnetic field sensing element. Various types of magnetic field sensing elements are known, including Hall Effect elements and magnetoresistance elements.
Magnetic field sensors provide information about a sensed ferromagnetic object by sensing fluctuations of the sensed magnetic field. Some magnetic field sensors include a fixed permanent magnet in a so-called “back bias” arrangement. Such magnetic field sensors sense fluctuations of the magnetic field associated with the permanent magnet as an object moves within a magnetic field generated by the magnet. In the presence of a moving ferromagnetic object, the magnetic field sensed by the magnetic field sensor varies in accordance with a shape or profile of the moving ferromagnetic object (a “target object”).
In automotive applications, a typical magnetic field sensor might determine a rotation of a target object, for example, a camshaft in an engine, and provide information about the rotation of the target object (e.g., an angle of rotation, etc.) to an engine control processor.
However, some current solutions can require complex processing by the magnetic field sensor to be able to determine the information about the rotation of the target object (e.g., an absolute angle of rotation, speed of rotation, direction of rotation, etc.). Such complex processing can require more expensive components and additional development expense. Some current solutions employ multiple magnetic field sensing elements or complexly shaped target objects, which also can increase complexity and cost. It would be desirable to provide a magnetic field sensor that can generate an output signal representative of an absolute relative rotational angle of the magnetic field sensor and a proximate target object. Therefore, an improved magnetic field sensor and target object arrangement is needed.